Code Migration for latest C++ Features.

[saurabhjangir]

As I am working on latest mongocxx-driver which needs c++ 11 feature to get compile successfully, I came across some auto_ptr related errors in mongodbBackend (Which is basically deprecated in C++ 11).
As a resolution we just need to study unique_ptr and replace it smartly with auto_ptr.
So just wondering if we're having any plans for the same ?

[fgalan]

Not sure if we already have an issue about migrating to c++11 (maybe you could have a look to the open issues to check it) but anyway it seems to be a good idea and, as far as a know, a pre-requisite for the MongoDB drive migration.

Thus, I think it would be a good idea to do that but before starting to work in the MongoDB driver migration. However, some questions I have about it:

• Appart from auto_ptr, is there any other "pattern" we should change in the current code base? How large would be the change?
• Is c++11 supported by CentOS 7 (the official OS for Orion)? I guess so, but we maybe we should ensure before starting this task

Thanks!

[saurabhjangir]

I didn't find any open Issue related to the migration.
Yes, As we know mongocxx driver needs c++11, so for compiling code with mongocxx latest driver we need to build the code with -std=c++11 flag, but while doing so I've found that mongodbBackend throws error because mongodbBackend uses auto_ptr at several places which is deprecated in C++ 11 . So for the current situation I have removed -Werror so that mongodbBackend don't throw any error while compiling it with C++ 11. As this is just a workaround, replacing auto_ptr with unique_ptr will be a better Idea.
Now coming to your questions,

• Apart from mongodbBackend (where auto_ptr is used ), rest of the code is building successfully with C++ 11 standards. Although I am just talking about compiling the code, I can't say anything about the run time behavior as I've not tested it yet. Hopefully apart from auto_ptr rest of the code is fine. We'll confirm it after testing only.

• Yes CentOS 7 support c++11.

Thanks :)

[fgalan]

It seems to be good news :)

Thus, I'd suggest going ahead with a PR replacing auto_ptr with unique_ptr. Behavior at run time will be checked by travis when you cast the PR with a pretty good coverage based on tests, don't worry about it.

[saurabhjangir]

That's great !! I'll share these changes ASAP.

[fgalan]

Not sure if we already have an issue about migrating to c++11 (maybe you could have a look to the open issues to check it) but anyway it seems to be a good idea and, as far as a know, a pre-requisite for the MongoDB drive migration.

The pre-requisite disappeared at the end because we are using a C-based driver. However, it may be a good idea to move to C++11 in some moment, so this issue stills.